Obinutuzumab Reduces Disease Progression Risk in CLL Study

Genentech announced the first results from CLL11, a Phase 3 study of the investigational drug obinutuzumab. The study is comparing the combination of either obinutuzumab or Rituxan (rituximab) and chlorambucil, a standard chemotherapy, to chlorambucil alone in chronic lymphocytic leukemia (CLL). The CLL11 study included elderly people with previously untreated CLL. Obinutuzumab is the first type 2 anti-CD20 drug glycoengineered to change its interaction with the body’s immune cells to assist the immune system in removing cancer cells from the body. It also binds to CD20 with the aim of killing cancerous cells directly.

CLL11 is a multicenter, open-label, randomized three-arm study investigating the safety and efficacy profile of either obinutuzumab added to chlorambucil or Rituxan added to chlorambucil compared to chlorambucil alone in 781 previously untreated people with CLL and comorbidities. The primary endpoint of the study was progression-free survival (PFS).

Addition of obinutuzumab to chlorambucil led to a statistically significant reduction in the risk of disease progression or death of 86% (HR=0.14; P<.0001). The median PFS improved by more than a year from 10.9 months for chlorambucil alone to 23 months for obinutuzumab plus chlorambucil. The addition of Rituxan to chlorambucil significantly reduced the risk of disease progression or death during study follow-up by 68% (HR=0.32; P <.0001). Median PFS was 10.8 months for chlorambucil compared to 15.7 months for Rituxan plus chlorambucil. No formal comparison between obinutuzumab and Rituxan arms has been made.

Previously the FDA had granted GA101 Breakthrough Therapy designation. Genentech will open an Expanded Access Program to provide obinutuzumab to people with CLL under certain circumstances while the company seeks regulatory approval.

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